Field of the Invention
The present invention relates to a medical assist device that assists biopsy or treatment by puncture with a needle-like instrument.
Description of the Related Art
Needs of minimally invasive treatment are increasing to improve the quality of life (QOL) of patients in medical care. Percutaneous therapies, such as percutaneous ablation therapy and percutaneous cryotherapy, have been developed as minimally invasive treatments.
In such a percutaneous therapy, puncture has to be performed based on medical images captured by an imaging such as magnetic resonance imaging (MRI) or computed tomography (CT) because the target site is not directly seen. These images are not captured in a real-time manner because such a medical imaging apparatus is used. A special MRI apparatus enables real-time image capture. In this case, an operation has to be performed in a narrow space. It is difficult to accurately reach a target in either of the above-described cases. This results in time-consuming operation.
Under the above-described circumstances, a puncture assist device as described in U.S. Patent Application Publication No. 2006/0229641 has been developed as an operation assist using medical images, such as MRI or CT images. As described in U.S. Patent Application Publication No. 2006/0229641, the device disposed on a patient's abdomen adjusts an insertion trajectory relative to the position of a puncture target site specified using medical images to puncture the target side. This device is positioned in any orientation and any angle by motors, and accordingly readily assists puncture in a correct direction. In addition, a holder for an instrument can be moved to an open position to achieve safety after puncture. Consequently, if organs shift due to breathing or the like of a patient, the organs will be protected from excess stress because the instrument is free.
A device including a ring-shaped vibration-type actuator as described in U.S. Patent Application Publication No. 2014/0275979 has been developed for use in combination with an MRI apparatus. In addition to the ring-shaped vibration-type actuator, other actuators have been developed. For example, U.S. Pat. No. 7,187,104, herein incorporated by reference in its entirety (see also Japanese Patent Laid-Open No. 2004-320846) describes a plate-shaped vibration-type actuator utilizing displacement in its thickness direction. Japanese Patent Laid-Open No. 8-237971 describes a plate-shaped vibration-type actuator utilizing displacement in its longitudinal direction. Japanese Patent Laid-Open No. 5-083961 describes a composite actuator that achieves longitudinal vibration and torsional vibration using individual piezoelectric elements.
Assuming that the instrument is released, if an operation error or malfunction of the device occurs while the instrument is partly placed in a patient's body, the holder may be moved beyond the open position. In such a case, the holder may apply a large external force to the instrument partly placed in the patient's body. Unfortunately, the device may suffer from excess stress.